1. Field of the Invention
The present invention generally relates to a device installed in a mining tunnel where coal, rock and the like are being mined to facilitate ventilation of the face area of the mine by providing a line curtain extender to enable the line curtain to be extended beyond the last permanent roof support without personnel installing temporary supports for the line curtain beyond the last permanent roof support thereby eliminating personnel occupying a danger area and at the same time effectively supporting a line curtain extension so that it can be extended to comply with regulations with respect to spacing of the line curtain in relation to the face area of the mine without interference with operation of the mining machine or the visibility capabilities of the mining machine operator.
2. Description of the Prior Art
The following U.S. patents are relevant to this invention:
U.S. Pat. No. 750,829, Feb. 2, 1904 PA1 U.S. Pat. No. 1,257,535, Feb. 26, 1918 PA1 U.S. Pat. No. 1,465,334, Aug. 21, 1923 PA1 U.S. Pat. No. 1,486,120, Mar. 11, 1924 PA1 U.S. Pat. No. 3,464,756, Sept. 2, 1969 PA1 U.S. Pat. No. 3,715,969, Feb. 13, 1973 PA1 U.S. Pat. No. 4,180,352, Dec. 25, 1979
Of the above-listed patents, the patents to Burgess and Divers et al. relate to mine ventilation in which a movable line curtain is employed and explains the manner in which a line curtain is employed in the ventilation system of a mine. The other patents listed above disclose various counterbalanced support structures and the like. Burgess, U.S. Pat. No. 3,464,756, includes a line curtain extension that is supported by a spring biased roller similar to a window shade roller with the free edge of the curtain being connected with the mining machine. Burgess, U.S. Pat. No. 3,715,969, discloses an extendible line curtain supported by vertical members and a horizontal rod received between rollers to enable the curtain to be advanced toward the face area of the mine. The Divers et al. patent discloses a support system for a curtain including a channel-shaped mounting member which includes a track with the mounting member being displaceable by virtue of its connection with the support assemblies. While the prior patents disclose the basic concept of providing an extendible line curtain in a mine ventilation system, the structural features of the prior patents and their operational capabilities are not equivalent to the structures and operational capabilities of the present invention.